An avalanche swept away climbers and their camps on the world's eighth highest mountain in northwestern Nepal on Sunday, killing at least nine climbers, with another four missing, police said.

Five climbers were rescued.

Police inspector Basant Mishra said the bodies of a German climber and a Nepali guide were recovered from the snow on the 8,163-metre Mount Manaslu, about 100 km northwest of Kathmandu.

"Rescue pilots have spotted seven other bodies on the mountain," Mishra said. At least five injured people had been rescued by helicopters and flown to Kathmandu, he said.

The accident took place at 7,000 metres, making it difficult for land rescue teams to reach.

Helicopters were dispatched to the remote area to look for those missing after the early morning accident, but cloud and fog were complicating rescue efforts, Mishra said.

Details of the avalanche and the nationality of the missing climbers were not clear.

Hundreds of foreign climbers flock every year to Himalayan peaks in Nepal, which has eight of the world's 14 highest mountains, including Mount Everest. September marks the beginning of the autumn climbing season which runs through November.

In the last major accident in the area, at least 42 people including 17 foreigners, were killed in heavy snowfall in the Mount Everest region in 1995.